LE3 .A278 2011

2011

Lukeman, Matthew

Acadia University

Bachelor of Science

Honours

Chemistry

Chemistry

The Laser Flash Photolysis of 3,4-dimethyl-1,1-diarylgermacyclopent-3-enes led to the formation of diarylgermylenes that were detected at 500 nm. The reactivity of these diarylgermylenes was studied with allyl chloride at 25⁰C in hexanes. The (1+2) cycloaddition of the diarylgermylenes to the unsaturated carbon-carbon bond of allyl chloride formed germiranes that were detected at about 280 nm. The rate constant of germirane formation, kQ, was found to be (4.7±0.2) x109 M-1s-1. The germirane decay was also studied and the rate constant of the decay, kdecay,1, was found to be (40±2) s-1. The electronic effects on kQ and kdecay,1 were investigated using Hammett correlations, and no significant electronic effects on either rate constant was found. This may be due to poor electronic communication between the large germanium centres of reactivity and the much smaller carbon rings. On a shorter time scale, an additional transient species was found during the reaction of the methylated diarylgermylenes with allyl chloride, having a λmax of 320 nm and a lifetime of 3 μs. It was proposed that this species was most likely the Lewis acid-base complex with electron pair donation from the halogen. The final product of the reaction between the diarylgermylenes and allyl chloride was the product of insertion of the diarylgermyelenes into the C-Cl bond. The rate constant for this insertion, kins, was equal to kdecay,1 if the germiranes decayed to the insertion product. If the germiranes had to break down to the diarylgermylenes and allyl chloride for the insertion to take place, kins was at least 1x106 M-1s-1.

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https://scholar.acadiau.ca/islandora/object/theses:795